Abstract: An apparatus consisting of stacked slab waveguides whose outputs are vertically staggered is disclosed. At the input to the stacked waveguides, the entrances to each slab lie in approximately the same vertical plane. A spot which is imaged onto the input will be transformed approximately to a set of staggered rectangles at the output, without substantial loss in brightness, which staggered rectangles can serve as a convenient input to a spectroscopic apparatus. A slit mask can be added to spatially filter the outputs so as to present the desired transverse width in the plane of the spectroscopic apparatus parallel to its dispersion.

Abstract: An apparatus consisting of stacked slab waveguides whose outputs are vertically staggered is disclosed. At the input to the stacked waveguides, the entrances to each slab lie in approximately the same vertical plane. A spot which is imaged onto the input will be transformed approximately to a set of staggered rectangles at the output, without substantial loss in brightness, which staggered rectangles can serve as a convenient input to a spectroscopic apparatus. A slit mask can be added to spatially filter the outputs so as to present the desired transverse width in the plane of the spectroscopic apparatus parallel to its dispersion.

Abstract: An apparatus is presented for stabilizing an optical, thermal, and mechanical interface between a spectroscopic and/or imaging system and a biological sample. The apparatus includes a window retainer having a retainer surface and a well. The retainer surface surrounds the well. Further, the retainer surface is substantially planar. An optical window is located in the well. The optical window comprises a first and second surface. The second surface is in contact with the window retainer. The first surface is substantially flush with the retainer surface. The apparatus further includes an attachment mechanism coupling the window retainer to the biological sample such that a fluid, gel, adhesive or elastomer interposed between the optical window and the biological sample is trapped in the well.

Abstract: An apparatus consisting of two pairs of identical lenses which is suitable as a compound objective lens for high numerical aperture imaging is disclosed. The compound lens also has a wide field of view as a fraction of the compound lens focal length. By suitable choice of lens materials, well corrected near infrared imaging can be achieved. When two such compound lenses together with a diffraction grating are assembled into a spectrometer, excellent wavelength resolution in the near infrared can also be obtained.

Abstract: An apparatus is disclosed wherein laser radiation illuminates a sample using all reflective optics and wherein in-elastically scattered light from the sample is collected using the identical elements. The apparatus obviates the problem of contaminating the laser radiation with unwanted spectra from transmissive optics while providing very high rejection of the laser radiation with respect to the in-elastically scattered light. In addition, the apparatus can collect and launch light with high numerical aperture and large field of view.

Abstract: The concentration of analytes in a complex mixture can be ascertained by spectroscopic measurement, even if the spectra of substances other than the analyte overlap with that of the analyte. Both independently measured concentrations of the analyte in a training set and of the analyte spectrum are used. Variances in the spectral data attributable to the analyte are isolated from spectral variances from other causes, such as compositional changes associated with different samples that are independent of the analyte. For the special case of noninvasive glucose measurements on the skin of biological organisms, the volume averaged glucose in the sample is predicted from the blood glucose. A test for over-fitting of the data is also described.

Abstract: An apparatus is presented in which a sample can be accurately repositioned in a spectroscopic and/or imaging apparatus upon multiple insertions, and where the apparatus can be worn by living subjects for extended periods of time. The apparatus additionally reduces the temperature increase and stabilizes the temperature of the sample upon irradiation with an optical source of excitation. Additionally, the apparatus stabilizes the pressure and critical optical properties of the sample and its interface with the apparatus. Alternatively or additionally, the apparatus can be used to alter and/or substantially reduce fluorescence from targeted fluorophores in the sample.

Abstract: The concentration of analytes in a complex mixture can be ascertained by spectroscopic measurement, even if the spectra of substances other than the analyte overlap with that of the analyte. Both independently measured concentrations of the analyte in a training set and of the analyte spectrum are used. Variances in the spectral data attributable to the analyte are isolated from spectral variances from other causes, such as compositional changes associated with different samples that are independent of the analyte. For the special case of noninvasive glucose measurements on the skin of biological organisms, the volume averaged glucose in the sample is predicted from the blood glucose. A test for over-fitting of the data is also described.

Abstract: An apparatus for enhancing the selectivity for spectroscopic measurements of analytes in a turbid medium is described. In one example, spatial filters are used to select only certain radii from the medium to be imaged. This selection is accomplished by placing an optical obstruction on the surface of the medium or at an image plane of the surface later in the optical imaging system. In one implementation, this is achieved by placing a fiber bundle at an image plane of the collecting optical system and then using a spacer of appropriate size at the center of the fiber bundle to act as a central obstruction.

Abstract: A method is proposed whereby photo-bleaching is used not only to change the absorption and fluorescence of a sample but is also employed to change its scattering characteristics. When the compounds which are bleached are contained in regions wherein the real part of the index of refraction is greater than or equal to the average index of the medium, the bleaching will result in reduction in the scattering at wavelengths longer than the wavelength of the bleaching source. This reduction can be useful in measuring the concentration of analytes located at significant depths within turbid media.

Abstract: An apparatus is presented in which a sample can be accurately repositioned in a spectroscopic and/or imaging apparatus upon multiple insertions, and where the apparatus can be worn by living subjects for extended periods of time. The apparatus additionally reduces the temperature increase and stabilizes the temperature of the sample upon irradiation with an optical source of excitation. Additionally, the apparatus stabilizes the pressure and critical optical properties of the sample and its interface with the apparatus. Alternatively or additionally, the apparatus can be used to alter and/or substantially reduce fluorescence from targeted fluorophores in the sample.

Abstract: A method is proposed whereby photo-bleaching is used not only to change the absorption and fluorescence of a sample but is also employed to change its scattering characteristics. When the compounds which are bleached are contained in regions wherein the real part of the index of refraction is greater than or equal to the average index of the medium, the bleaching will result in reduction in the scattering at wavelengths longer than the wavelength of the bleaching source. This reduction can be useful in measuring the concentration of analytes located at significant depths within turbid media.

Abstract: An apparatus for enhancing the selectivity for spectroscopic measurements of analytes in a turbid medium is described. In one example, spatial filters are used to select only certain radii from the medium to be imaged. This selection is accomplished by placing an optical obstruction on the surface of the medium or at an image plane of the surface later in the optical imaging system. In one implementation, this is achieved by placing a fiber bundle at an image plane of the collecting optical system and then using a spacer of appropriate size at the center of the fiber bundle to act as a central obstruction.

Abstract: An optical apparatus in which multiplexed holograms are used to achieve wavelength selectivity and polarization manipulation is used to facilitate near-normal incidence of light on the holograms. The polarization manipulation allows light reflected from the holograms to be separated from the light incident on the holograms. In one application, the apparatus can be used to extract spectral lines of an analyte from radiation scattered from a sample.

Abstract: Weak signals scattered from analytes at multiple wavelengths can be summed to illuminate either a single detector or a multiplicity of detectors, offering the possibility of concentrating the spectral energy on a smaller total detector area. In addition, a method is disclosed whereby a calibration of the resulting signal for a given analyte can be obtained by means of measuring the quantity of water in the sample volume and by means of measuring the salinity of the fluid in the sample volume.

Abstract: An apparatus is described in which the temperature of a semiconductor laser (or other device) can be set to a desired value by using the heat generated by the laser itself in conjunction with an adjustable thermal impedance heat sink to effect the desired temperature rise.